The documentation in invoke.texi for the --help= option only lists the "optimizers", "warnings", "target", and "params" values that the option can take. However, it can also take a language name as a value, and this isn't documented.
-- Summary: --help=<language> option isn't documented. Product: gcc Version: 4.3.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: other AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: brooks at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31355